1. Field of the Invention
The present invention relates to an image pickup apparatus for picking up an object image.
2. Related Background Art
As for this type of image pickup apparatuses in the past, there are those already put on the market, such as an electronic camera with a memory card having a solid-state memory device as a recording medium for recording and reproducing still images and moving images picked up by solid-state image pickup elements such as CCD, CMOS and so on.
In general, this type of image pickup apparatus is comprised of a pixel portion, a read-out circuit portion and an output portion, and is placed on a single substrate (on-chip) for the sake of reducing noise.
As for the image pickup elements in the past, however, since the read-out circuit portion, output portion and pixel portion are on the single substrate, in the case where accumulation time becomes a long time in minutes, heat is generated by the output portion and the like of the image pickup elements, which consume a lot of currents, and dark currents locally increase due to increase of thermal noise and a local temperature rise in the pixels close to the output portion, thereby resulting in lower image quality.